@padders : no one could fault you for not paying close attention to this (though you did just on another thread give me a very clear, detailed, almost impassioned, explanation of how the beats of the speedmaster movements do or do not align with the sub-indexes of different dial variations - thank you for it).

My own observation (echoed by others) is that the qualitative difference between the std sapphire and cal.321 sapphire and that the latter lacks a remarkable amount of the much maligned “milky ring” type qualities of the former. And if true, that would seem to knock out several (not all) of most often cited complaints in the preference (war) between plexi and sapphire.

My hypothesis (but by no means theory) is that the ibove observation results from something about the engineering of the marketed “domed” sapphire of the cal.321, possibly in tandem with other features (e.g. the rehaut).

But as far as obvious, agreed, and verifiable quantitative differences between the two sapphires: you’re correct that it boils down to the engraved logo ... so far?

 

I didn’t mean to ridicule with my comment I actually think the level of obsession with details is endearing on this forum.

Anyway I saw this pic posted on FB. It appears to be clear that the new sapphire 3861 does not have the 321 crystal. It’s too bad, because if they had put a ceramic bezel and the domed sapphire on the 3861, while leaving the aluminum bezel to the hesalite version, then the sapphire 3861 might actually be a true Daytona competitor. But—I think that’s what the 321 is for.

so you’ve got hesalite for the purists who want more retro, sapphire 3861 for those who want some modern with their retro and don’t mind the milky ring, and the 321 for the true nerds who also want the highest quality, and are willing to pay for it. The 321 has always seemed sort of like a singer 911 to me.

 

I ginned up this using your stolen picture ("he stole it, I only borrowed it"), and my own picture from yesterday of my cal.321.



It's not a perfect comparison of course (for that we'll need someone with all three to take a photo under all similar lighting, white balance, etc.) - but until then, I think it suffices to provide as much qualitative data as ever justifies the majority of opinions around here.

My quick take-aways:

(1) As for comparing the sapphire on the cal.321 and cal.3861 sapphire: while my cal.321 picture may have in some way been optimized to reduce the milky ring (though I didn't particularly work at it except to avoid my own reflection in the sapphire), I don't think I've ever seen a photo of a modern sapphire speedy that didn't have the milky ring also evident in this photo's .3861 sapphire.

(2) As for comparing the cal.321 and cal.3861 plexi: for my money, crystal wise, these appear far more similar than the two sapphires

(3) As for comparing the .3861 sapphire vs plexi: based on this picture at least, I'd be going plexi (but would prefer to have both!)

 

There's no doubt that the shape of the crystal, in particular how "sharp" the corner is where the vertical sides meet the domed portion, will influence the transmission of light (the milky ring).

Few years ago someone (can't recall who) emailed me saying that they recalled when the first sapphire Speedmasters came out that the "milky ring" was less prominent than it was currently. This lead to a deep dive in looking for various parts associated with sapphire crystals, and in the end one thing that seemed to be a factor was the crystal gasket.

So I remembered this today and sure enough the gasket used in the "old" 1861 sapphire Speedmasters is grey. The 3861 new version uses a black gasket, and also the one for the 321 is black. Material doesn't change (Hytrel) but the colour does...so this is another factor.

 

There was a discussion here that the 2007 Sapphire sandwich 3573.50 had less "milky ring" compared with the 2017 sapphire sandwich.
https://omegaforums.net/threads/hesalite-vs-sapphire-speedmaster-pro-pics.85579/page-5

i quote @robinhook:
Ok guys... I guess this is a rather rare opportunity so we don’t see much of this comparison on the internet. But I got a hold of a early production 2007 sapphire sandwich 3573.50, and compared it with my current production 2017 sapphire sandwich 311...006. The difference is shocking.

The shape of the crystal is significantly different, resulting the 2017 one having a evident “milking ring”, while the 2007 one looks almost like a hesalite crystal... I don’t think I need to tell you which one is which in the picture... stunning

I don’t know what to make out of that.. I can compare it later with my hesalite, to be continued...




Ok... from left to right:
1. Hesalite 3570.50
2. Sapphire 3573.50 - 2007
3. Sapphire 311...006 - 2017

I think this 2007 3573.50 is really quite special.



Here are the side view comparison. From the top to bottom:
1. Hesalite
2. Sapphire 3573.50 2007
3. Sapphire 311...006 2017

 

I think this is THE factor

 

Don't think twice about it. We love our pets and posting pictures of the watch we are wearing but very few people join here for that reason. We join for threads like this.

Thanks for sharing your contributions.

Dave

 

In the previous thread provided above by @STANDY, member @Longbow had posted the below pictures (1) and (3) of the prior speedy plexi/sapphire; I stole his pics (thank you), and created the new pic posted below - now including a profile of the cal.321

Watches shown below are in order:
(1) 1861 Hesalite Speedy
(2) New cal.321
(3) 1861 Sapphire Speedy (Tokyo)



It's probably obvious that I've arranged the three watches in an order. Using @Longbow 's pictures, it is clear the cal.321's sapphire has a steeper slope at the margins than does the 1861 plexi, but far less steep than the 1861 sapphire.

And as @Archer said:

Sure enough, this expected outcome is observed in the cal.321 having significantly less milky ring (no milky ring?) than does the previous 1861 sapphire.

It's possible that additional features of the cal.321 contribute to an additional reduction of the milky ring, but I'm at this point fairly confident that the 'domed' shape of the cal.321's sapphire is a significant contributor.

This conclusion mirrors that discussed in the awesome thread posted above by @Eve (of @robinhook comparing the 'unique' qualities of the Sapphire 3573.50 2007). I also stolen @robinhook 's photos for the below mashup, putting my above pic side-by-side with his:



The pattern is pretty obvious, including the similarities of the cal.321 sapphire and the 'unique' Sapphire 3573.50 2007. Interestingly, it appears that the cal.321 has an even less steep slope than the Sapphire 3573.50 2007 - which we'd expect to result in the cal.321 having even less milky ring than the 3573.50 2007.

Up to now, I would have pretty quickly recited that a key consideration between plexi and sapphire is the issue of the "milky ring." Now I'd ask, "what type of sapphire?"

It's still true that the rest of the crystal, as between plexi and sapphire, will betray the other optical differences between the two: differences in reflections, clarity, scratches, etc.

But the plexi devotee's often employed quip about the "terrible milky ring" might be often true, but not always true (depending on the shape of the sapphire - potentially together with other factors such as the rehaut, gasket, etc.)

 

I agree with @Archer that the color of the gasket is surely a factor.

But I would not agree (and assume @Archer would not agree) that it is the factor.

Consider again the photo of the new 3861 sapphire with black gasket (far left) compared to the cal. 321 with the same black gasket (far right):



Whatever work the shared black gasket does in reducing both watch's milk ring, there is still a clear difference remaining.

 

Nice summary. I think buyers of 321 would not have been happy with a milky ring, and they probably would mostly have not been happy with hesalite on a watch at that price point. So Omega managed to find a happy medium with that crystal.

But it would have been nice if they applied that crystal to the new 3861 watch. Especially on the precious metal versions, the milky ring might spoil the experience a bit.

 

As true for most of life, it's not a simple yes or no.

I suspect you've given hesalite fans a lot to ponder. Unless we're floating in zero gravity and can't take the chance of shattered sapphire, we Earth bound watch wearers have reasons to reconsider sapphire.

 

I would be interested to get profile pictures of both new models, to create the above type of tryptic [EDIT: triptych!] comparison. Perhaps the new cal. 3861 sapphire is still yet different from the prior model - but based on front-on pictures I've seen so far, I predict it to look much more like the prior model than the cal. 321.

 

For fun, a different “milky ring” problem (of Rolex Deep Sea Special prototypes)

 

@Archer, could you maybe post pics of unmounted sapphire crystals you might have? I'm interested in the finish of the sides (the cylindrical area that defines the overall diameter of the crystal). I'm guessing that surface is milky in appearance (diffusely reflective), and there is either a difference in roughness, and/or a difference in height of the diffusely reflecting surface between crystals.

It might also be interesting to see whether painting that area black before mounting the crystal, or optically coupling it to an optically absorbing surface, or polishing it makes a difference. Polishing is a bit labor intensive; the least destructive option would be to apply some optical grease and put a matte black surface (paper; graphite powder) in contact with that area and take before/after pics looking for the appearance of the milky ring.
If one of these techniques works, you could offer 'milky ring removal' as a service to your customers...

 

Why do you guess that?

 

I don't have spare crystals - not something that I would stock given the price of these...

I don't remove these often, so honestly I can't recall what the sides of the crystal look like. It is typical with crystals on dive watches that the outer diameter is a sort of frosted finish, and this acts to help increase the friction between the crystal and gasket to hold it in place.

 

Since @Archer has since weighed in, I’ll see if I understand the point of your question better:

My assumption is that you were wondering whether any such frosting of a portion of the perimeter of the sapphire contribute to a milky appearance?

If so, and considering as well @Archer’s confirmation of my suspicion, I do not think any such frosting of the sapphire, if exists, would lead to a milky appearance.

This is because if any such frosting exists, once seated in the bezel. it would exist below the visible portion of the crystal. Moreover, to the extent below the bezel, it may be fully in contact with gasket. In all instances. Such frosting would be out of contact with light passing through it to the viewer (only light would pass through the crystal toward the frosted).

Any portion of the crystal above the bezel, and visible to the wearer, would not be frosted: as is seen in this picture:



But do please let me know if I’ve misunderstood your suggestion, or you think I have something wrong

 

Archer, cvalue13, thank you for the replies, and Happy New Year!

Al, I had not considered that crystals wouldn't be a frequently serviced item. I somehow assumed, with you running near capacity and having to turn work down, they would be coming across your desk every week or so. i guess crystals are sturdier than I thought.
I did consider the risk of experimenting with high priced items - hence the suggestion of 'minimally invasive' work with optical grease. Still, if you come across the crystals of the different types, if you could take a pic (or two: one from the top, with lighting from the side, to provoke the milky ring, and one from the side, to show the frosted (or not) outer diameter surface), that would be very much appreciated.

Cvalue13, no, you understood correctly. My thinking is that sapphire has a very high index of refraction (1.78 to 1.76 over the visible range; see for example https://refractiveindex.info/?shelf=main&book=Al2O3&page=Malitson ), so you get a lot of trapping of light due to total internal reflection at surfaces to air, but also at boundaries to other media of lower refractive index (like glue). A higher fraction than for mineral glass or plexiglass (with n of 1.4 to 1.6 or so). The light can escape in areas of high curvature (like the corner of a box shaped crystal). I'm guessing that the milky ring is the image of the frosted outer diameter surface seen through the high curvature edge of the crystal.

Any of three factors
- less light trapped due to lower index of refraction of the type of glass/plastic
- less reflected light from the frosted/milky surface, due to smaller height or better polishing or more absorbent material in contact with the crystal
- less concentration of escaping light due to larger radius of curvature at the edge of the crystal

could reduce the milky ring. But that's all just guessing, and Al could get us the experimental answer.

It's a bummer there are no Omega engineers on this board. They must have run simulations for this. Or at least they should have...

 

Cvalue13, I forgot to say that it's surprisingly difficult to get rid of light. Just because it goes down into the cylindrical part of the crystal towards the gasket doesn't mean it's going to get absorbed down there.

 

Since the vast majority of Speedmasters I service have acrylic crystals, I actually don’t see all that many sapphire versions, maybe 2 or 3 per year, but the rest are typically acrylic.

Unlike acrylic crystals, the sapphire rarely need replacing, and that is the only reason to remove it from the case. The case can be cleaned, the bezel removed, the pushers exchanged...none if this normal work requires removing the crystals, so I don’t do it just for fun...

But should there be a need, I will take photos for you...